A CONVERSATION WITH | STEPHEN HAWKING Life and the Cosmos, Word by Painstaking Word

TEMPE, Ariz. — Like Einstein, he is as famous for his story as for his science.

This week: A rare interview with a physics superstar, and up in the trees with a sleeping bird.

At the age of 21, the British physicist Stephen Hawking was found to have amyotrophic lateral sclerosis, Lou Gehrig’s disease. While A.L.S. is usually fatal within five years, Dr. Hawking lived on and flourished, producing some of the most important cosmological research of his time.

In the 1960s, with Sir Roger Penrose, he used mathematics to explicate the properties of black holes. In 1973, he applied Einstein’s general theory of relativity to the principles of quantum mechanics. And he showed that black holes were not completely black but could leak radiation and eventually explode and disappear, a finding that is still reverberating through physics and cosmology.

Dr. Hawking, in 1988, tried to explain what he knew about the boundaries of the universe to the lay public in “A Brief History of Time: From Big Bang to Black Holes.” The book sold more than 10 million copies and was on best-seller lists for more than two years.